A reversal process or a photographic process for directly obtaining positive images without using any negative film is well known.
As a process for directly forming positive images with an internal latent image type silver halide emulsion, there are various known arts, for example, those disclosed in the specifications of U.S. Pat. Nos. 2,592,250; 2,466,957; 2,497,875; 2,588,982; 3,317,322; 3,761,266; 3,761,276; 3,796,577; British Patents 1,51,363, and 1,150,553.
In general, direct positive color photographic materials containing internal latent image type silver halide emulsion layers which are not previously fogged are processed by carrying out image-wise exposure, then fog-exposure prior to or during development using a surface color developing solution containing an aromatic primary amine color developing agent and/or development using the surface color developing solution in the presence of a nucleating agent, bleaching and fixing.
The improvement of image quality, particularly that of sharpness is the important aim of the direct positive photographic materials, which has been studied in various aspects.
As one of the means of achieving the above improvement, there is known the use of irradiation-preventing dyes. Pyrazolone 1-position sulfoaryl type dyes are described in JP-B-51-46607, JP-B-39-22069, JP-B-60-53304 and JP-B-55-10061 (the term "JP-B" as used herein means an "examined Japanese patent publication"). The cases using pyrazolone 1-position sulfoalkyl type dyes are illustrated in JP-B-55-10059 and JP-A-51-32325 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
However, the application of these dyes to previously-not-fogged internal latent image type direct positive photographic materials may improve the sharpness but undesirably cause desensitization when preserved for long periods of time or at high temperature. In particular, the preservation thereof at relatively high temperature causes remarkable desensitization. On the other hand, pyrazolone 1-position sulfoaralkyl types dyes are disclosed in JP-A-50-145125 (corresponding to British Patent 1,466,836), JP-A-50-144712 (corresponding to U.S. Pat. No. 3,989,528), and JP-A-52-20830 (corresponding to British Patent 1,553,516), but the application thereof to the previously-not-fogged internal latent image type direct positive photographic materials is not mentioned at all.